The present invention generally relates to assemblability discriminating methods and assembling sequence generating methods, and more particularly to an assemblability discriminating method for discriminating assemblability of parts and an assembling sequence generating method for generating an assembling sequence of parts.
The present invention is applicable to computer-aided design (CAD) for computer-integrated manufacturing (CIM) using a technique called systematic decomposition of manufacturing (SYDEM) of a completed product.
Recently, more and more robots are used at various locations within a factory in combination with numerically controlled (NC) machines. With the progress in factory automation (FA), a number of workers who take part in a manufacturing process decreases. As a result, matters which do not cause any problems when a manufacturing process involves a manual operation by man often become unsolvable problems when the same manufacturing process is carried out solely by a robot. Such problems occur because the automated machines are awkward and lack adaptability and intelligence when compared with human workers. In order to overcome such problems, it is necessary that the problems which may occur during the manufacturing processes are checked and decisions are made to avoid the problems in advance, that is, in a designing stage.
The CAD is concentrated around computational geometry and especially on solid modeling which aims at defining a shape of a mechanical part. Many of the CADs for commercial use is developed based on the solid modeling. A mechanical object assembled from a plurality of parts is called an assembly. Although the assembly is essential to the product manufacturing, research on the designing of the assembly is less active when compared to research related to the solid modeling.
Ishida et al., "Detection of Unanticipated Functions of Machines", Proc. International Symposium on Design and Synthesis, July 11-13, 1984, pp.2l-26 discusses the assemblability of machines as disassemblability of machines. However, according to the method proposed in Ishida et al., only the machine per se is considered and no consideration is given on an assembling environment.
On the other hand, Lund et al., "Design for Assembly", Proc. 4th International Conference on assembly Automation, 1983, pp.333-349 proposes a rational design for the assembly, but the design according to this method is based on experience for facilitating the assembling and makes no evaluation of a particular design.
Accordingly, Miyakawa et al., "The Hitachi Assemblability Evaluation Method (AEM)", Proc. 1st International Conference on Product Design for Assembly, 1986 proposed a method of evaluating the assemblability of a particular design, but this method also does not consider a particular assembling environment.
On the other hand, M. Brady, "Artificial Intelligence and Robotics", Artificial Intelligence, Vol.26, No.l, April 1985, pp.79-121 discusses a path-detection technique. This path-detection technique is used to generate an operation of an arm of a robot which assembles a part on a semi-completed product which is placed on a base under a particular environment. However, this technique is merely a simulation of assembling parts. There is no suggestion to combine the path-detections to discriminate the assemblability and to generate the assembling sequence.